1. Field of the Invention
The present invention relates to a method for controlling a defrost heater of a refrigerator by which defrosting is performed under the on/off control of the defrost heater without continuously heating the defrost heater during a defrost operation, and more particularly, to a method for controlling a defrost heater of a refrigerator by which a temperature rise in a freezing chamber during defrosting is minimized and ice formation in the freezing chamber is minimized for thereby reducing power consumption.
2. Description of the Background Art
Usually, when a refrigerator is operated, articles of food in the refrigerator is frozen(refrigerated). However, in the case where the refrigerator is operated for many hours, its cooling function may not be properly performed because frost and the like are formed in the refrigerator. At this time, a defrost operation is performed by the refrigerator according to a predetermined accumulated operating time of the refrigerator, for thereby normally operating the refrigerator. Here, the above-mentioned defrost operation of the refrigerator will be described.
FIG. 2 is a flow chart of a method for controlling a defrost heater of a refrigerator according to the conventional art. As illustrated therein, the above method includes: a first step of accumulating the run time of a compressor during the operation of the refrigerator; a second step of turning a defrost heater on when the accumulated run time of the compressor reaches a predetermined time; a third step of sensing the temperature of the defrost heater and checking if it reaches a predetermined defrost-off temperature when the defrost heater is on in the second step; and a fourth step of turning the defrost heater off if the sensed temperature of the defrost heater is the defrost-off temperature, or continuously performing the defrost operation if it does not reach the defrost-off temperature.
As illustrated in FIG. 1, a circuit for driving a defrost heater of a refrigerator according to the conventional art, in order to perform the method including the above-described steps, includes: a microcomputer 10 for accumulating the run time of a compressor during the driving of the refrigerator and outputting a control signal for controlling the operation of each unit required to remove frost on a cooler according to the above accumulated time; a defrosting sensor attached around the cooler for sensing the temperature of the cooler; a defrost heater 50 attached to the cooler and turned on to remove frost on the cooler if needed; an inverter 30 for inverting and outputting the output signal of the microcomputer 10 for controlling the defrost heater 50; and a relay 40 for controlling the on/off operation of the defrost heater 50 according to the output of the inverter 30.
The thusly described method for defrosting a refrigerator according to the conventional art will now be described in more detail.
When the refrigerator is driven by applying power, the microcomputer 10 counts the run time of the compressor of the refrigerator using an internal timer, and accumulates the counted time.
When the thusly accumulated run time of the compressor of the refrigerator reaches seven hours, the microcomputer 10 turns the defrost heater on by outputting a control signal of a high state to its output port 01 in order to remove frost adhered to the cooler.
The defrost heater used in the above is a sheathed heater, glass tube heater, or the like.
The control signal of the high state outputted from the output port 01 of the microcomputer 10 is inverted by the inverter 30 and becomes a control signal of a low state.
Accordingly, current flows in a relay coil of the relay 40, and thus a relay switch connected with an a-b terminal is switched over to an a-c terminal for thereby providing power to the defrost heater 50.
Consequently, the defrost heater 50 is turned on to be continuously heated.
When the defrost heater 50 is continuously heated in this way, the defrosting sensor 20 attached around the cooler senses the temperature of the cooler, and transmits the signal of the senses temperature to an analog/digital input terminal AD1 of the microcomputer 10.
Then, the microcomputer 10 recognizes the temperature of the cooler by converting the signal of the sensed temperature inputted into the analog/digital input terminal AD1 and reading the same.
As a result of the recognition, when the temperature of the cooler goes up enough to reach a predetermined defrost-off temperature at a point of time that defrosting is almost finished, the microcomputer 10 outputs a control signal of a low state to its output port 01.
The control signal of the low state from the output port 01 of the microcomputer 10 is converted to a high state by the inverter.
Consequently, current does not flow in the relay coil of the relay 40, and thus the relay switch connected with the a-c terminal is switched over to the a-b terminal for thereby disconnecting power provided to the defrost heater 50.
Hence, the defrost heater 50 is turned off to finish the defrosting.
As illustrated in FIG. 2, with respect to the above-described operation, the microcomputer 10 checks if seven hours elapse or not by counting the run time of the compressor of the refrigerator and accumulating the same in S101.
As the result of the checking, the defrost heater 50 is turned on to be operated in order to remove the frost adhered to the cooler when seven hours elapse in S102.
A defrost operation is performed for a predetermined time by turning on the defrost heater and melting the frost on the cooler, and thereafter it is checked if the temperature of the cooler has reached the defrost off temperature by sensing the temperature of the cooler in S103.
Herein, if the defrost-off temperature is reached, the defrost heater is turned off in S104 to stop the defrost operation for thus performing a freezing operation, or if the defrost-off temperature is not reached, the defrost heater remains to be on to perform the defrosting operation.
The above-described operation is repeated in such a manner that the defrost heater 50 is turned on every seven hours for thus performing the defrost operation.
However, in the above-described conventional art, since the sheathed heater and the glass tube heater for use in the refrigerator have very high heating temperature where the heater is continuously driven during defrosting, there is a disadvantage that the increased in power consumption, rising in temperature in the freezing chamber, and the occurrence of ice formation in the freezing chamber, but shortage of the defrosting time.
Accordingly, it is an object of the present invention to provide a method for controlling a defrost heater of a refrigerator which makes it possible to prevent the increase in power consumption, increase in temperature in a freezing chamber, and ice formation in the freezing chamber occurred due to the defrosting temperature rapidly increased by continuously driving the heater.
It is another object of the present invention to provide a method for controlling a defrost heater of a refrigerator which makes it possible to remove frost on a cooler using the quantity of heat during heater-on time and the latent heat during heater-off time under the on-off control of the defrost heater.
To achieve the above objects, there is provided a method for controlling a defrost heater of a refrigerator according to the present invention which includes the steps of:
accumulating the run time of a compressor and checking whether accumulated time has reached a predetermined time for defrosting;
performing a defrost operation, if the predetermined time for defrosting is a first defrosting point of time;
checking the current state of the defrost heater if the predetermined time for defrosting is not a first defrosting point of time;
turning on the defrost heater to perform the on/off control of the defrost heater, if the defrost heater is turned on/off and thereafter the on/off time reaches a predetermined time;
and turning off the defrost heater to finish the defrost operation, if the temperature of cooler has reached a defrost-off temperature during the on/off control of the defrost heater.
Additional advantage, objects and feature of the invention will become more apparent from the description which follows.